Refrigerant compressor for motor vehicles

ABSTRACT

Improvement for a refrigerant compressor comprising a compressor housing having at least two cylinder bores, pistons in the cylinder bores, a drive shaft chamber and a piston drive shaft in the drive shaft chamber such that this can operate with amounts of lubricant which are as small as possible, it is suggested that in the installed position of the refrigerant compressor the drive shaft chamber form a collection chamber for lubricant with an area which extends over only part of the extension of the drive shaft chamber and is located at the lowest point in the direction of gravity, that the drive shaft chamber have wall surfaces which adjoin the collection chamber and guide the lubricant accumulating in the drive shaft chamber to the collection chamber, and that a lubricant conveying device take up the lubricant from the collection chamber and convey it to lubrication points.

This patent application is a continuation of International application No. PCT/EP2004/012839 filed on Nov. 12, 2004.

This patent application claims the benefit of International application No. PCT/EP2004/012839 of Nov. 12, 2004 and German applications No. 103 54 529.8 of Nov. 17, 2003 and No. 103 58 471.4 of Dec. 10, 2003, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto.

BACKGROUND OF THE INVENTION

The invention relates to a refrigerant compressor for motor vehicles comprising a compressor housing, at least two cylinder bores which are arranged in the compressor housing, pistons arranged in the cylinder bores, a drive shaft chamber arranged in the compressor housing as well as a piston drive shaft arranged in the drive shaft chamber.

Refrigerant compressors of this type are known from the state of the art.

The problem with them is that they require very large amounts of lubricant in order to ensure reliable lubrication at all the lubrication points.

Large amounts of lubricant have, however, the disadvantage that refrigerant is dissolved in the large amounts of lubricant and this is outgassed again when the compressor is started and, therefore, leads to lubrication problems on account of the frothing of the lubricant.

Furthermore, the refrigerant dissolving in the lubricant leads to a deterioration in the lubricating properties of the lubricant.

The object underlying the invention is, therefore, to improve a refrigerant compressor of the type described at the outset in such a manner that this can operate with amounts of lubricant which are as small as possible.

SUMMARY OF THE INVENTION

This object is accomplished in accordance with the invention, in a refrigerant compressor of the type described at the outset, in that in the installed position of the refrigerant compressor the drive shaft chamber forms a collection chamber for lubricant with an area which extends over only part of the extension of the drive shaft chamber and is located at the lowest point in the direction of gravity, that the drive shaft chamber has wall surfaces which adjoin the collection chamber and supply the lubricant accumulating in the drive shaft chamber to the collection chamber and that a lubricant conveying device takes up the lubricant from the collection chamber and conveys it to lubrication points.

With the collection chamber according to the invention, which extends over only part of the extension of the drive shaft chamber, it is possible to reduce the amount of lubricant required for functioning of the lubricant conveying device and, therefore, to likewise diminish the problems inherent in the known, large amounts of lubricant.

A particularly favorable solution provides for the wall surfaces to essentially guide all the lubricant accumulating in the drive shaft chamber to the collection chamber so that it is ensured, as a result, that lubricant, which cannot be taken up by the lubricant conveying device in recesses provided next to the collection chamber but would lead to an increase in the amount of lubricant required, does not collect in these recesses.

A particularly expedient solution provides for some of the wall surfaces to extend at an angle to a drive shaft axis of the piston drive shaft in order to reduce the extension of the collection chamber in the direction of the drive shaft axis as a result.

A solution which can be accomplished particularly favorably from a constructional point of view provides for the collection chamber to border on a housing cover of the compressor housing.

In order to be able to assemble the compressor housing in a simple manner, the housing cover is preferably arranged such that it extends transversely to the drive shaft axis of the piston drive shaft.

In order to also be able to collect all the lubricant accumulating in the compressor housing via the drive shaft chamber, it is provided for the drive shaft chamber to be located beneath a cylinder chamber of the compressor housing in the direction of gravity in the installed position of the compressor.

The cylinder chamber is also preferably designed in such a manner that lubricant accumulating in it essentially enters the drive shaft chamber and, therefore, essentially no additional collection chambers whatsoever, which retain the lubricant and, therefore, contribute altogether to an increase in the amount of lubricant without improving the lubrication of the refrigerant compressor according to the invention, are formed in the cylinder chamber.

In principle, it would be conceivable with the solution according to the invention to form the wall surfaces and the collection chamber by way of an insert provided in the compressor.

A particularly favorable solution from a constructional point of view provides, however, for the collection chamber to be integrally formed in a drive shaft section of the compressor housing.

Furthermore, it is likewise favorable when the wall surfaces guiding the lubricant to the collection chamber are integrally formed in the drive shaft section.

A particularly expedient solution from a constructional point of view provides for the drive shaft section of the compressor housing to form a pan inclined towards the collection chamber.

In order to be able to insert the refrigerant compressor according to the invention into motor vehicles without any problem, it has proven to be particularly expedient when the collection chamber always remains the subsection of the drive shaft section located at the lowest point with an inclination of a drive shaft axis of up to at the most plus/minus 35°, in particular, up to at the most plus/minus 15° in relation to the installed position.

In addition, it is also favorable when the collection chamber always collects the lubricant with an inclination of the compressor housing about the drive shaft axis of the piston drive shaft of up to at the most plus/minus 90°, in particular, at the most plus/minus 45° in relation to the installed position.

With respect to the design of the lubricant conveying device, no further details have so far been given. In principle, it would be conceivable to use any conventional lubricant conveying device.

A solution which is particularly favorable on account of its constructional simplicity provides for the lubricant conveying device to comprise a lubricant pitching disk engaging in the collection chamber.

Such a lubricant pitching disk could be driven by means of a suitable drive. A particularly expedient solution provides for the lubricant pitching disk to be arranged by the piston drive shaft.

It is particularly simple from a constructional point of view when the piston drive shaft bears the lubricant pitching disk.

With respect to the arrangement of the lubricant pitching disk, no further details have so far been given. For reasons of an advantageous overall concept, it has proven to be expedient when the lubricant pitching disk is arranged close to the compressor housing cover located nearest to the collection chamber.

The lubricant pitching disk is preferably located such that it extends essentially vertically in the installed position.

In the case where a lubricant pitching disk is provided, the lubricant conveying device is designed in such a manner that it preferably has, in the compressor housing, a receiving chamber for lubricant pitched by the lubricant pitching disk.

In order to fill the receiving chamber with lubricant, the receiving chamber is preferably arranged such that lubricant pitched against a collecting surface and running down it enters this chamber.

In principle, it would be conceivable to arrange the collecting surface and the receiving chamber at any suitable location of the compressor housing.

One particularly advantageous solution provides for the receiving chamber to be arranged in the housing cover.

Furthermore, an additional, advantageous solution provides for the collecting surface to be arranged on the housing cover.

In order to improve the introduction of the lubricant collected by the collecting surfaces into the receiving chamber, it is preferably provided, in addition, for the lubricant conveying device to have guide ribs which guide the lubricant into the receiving chamber.

The supply of lubricant to at least some of the lubrication points could be brought about, for example, by way of channels provided in the compressor housing.

One particularly favorable solution provides, however, for the lubricant conveying device to comprise a central lubricant channel integrated into the piston drive shaft. The individual lubrication points of the piston drive shaft may be supplied with lubricant in a particularly simple manner due to such a central lubricant channel of the piston drive shaft.

The supply of lubricant to the central lubricant channel may be realized, in particular, from a constructional point of view when lubricant can be supplied to the central lubricant channel from the receiving chamber.

In this respect, it is particularly favorable when the receiving chamber borders directly on the piston drive shaft at its end side and, therefore, the lubricant channel opens directly into the receiving chamber.

In order to supply the individual lubrication points of the piston drive shaft, it has proven to be expedient when the central lubricant channel is provided with lubricant supply channels for lubrication points of the piston drive shaft which extend transversely to the lubricant channel.

These lubricant supply channels extending transversely to the central lubricant channel improve the conveyance of lubricant since a centrifugal force acts on the lubricant located in the lubricant supply channels as a result of the rotation of the piston drive shaft and this force conveys the lubricant to the respective lubrication points radially to the central lubricant channel and so a pumping action results thereby.

With respect to the filling amount of lubricant present altogether in the refrigerant compressor according to the invention, no further details have so far been given. The filling amount may be advantageously reduced in the case of the solution according to the invention in such a manner that this is less than double the capacity of the refrigerant compressor.

It is even more advantageous when the filling amount of the lubricant is less than 1.5 times the capacity of the refrigerant compressor.

Alternatively or in addition to the embodiments described thus far, the object cited at the outset is also accomplished in accordance with the invention by a refrigerant compressor of the type described at the outset in that the piston drive shaft is mounted in the compressor housing only in slide bearings and that the slide bearings have slide coatings with lubrication deficiency properties.

As a result of such slide coatings with lubrication deficiency properties it is possible to reduce the filling amount of lubricant to such an extent that even interruptions in the supply of lubricant can occur from time to time without damage resulting in the area of the slide bearings.

In addition, the slide bearings have the advantage that they have an improved stability with respect to vibrations, in particular, idle time vibrations.

In order to form additional lubrication points with lubrication deficiency properties with the solution according to the invention, it is also preferably provided for drive elements for the pistons to be mounted on the piston drive shaft with slide bearings which have slide coatings with lubrication deficiency properties.

Slide coatings of this type with lubrication deficiency properties may be provided, for example, on the piston drive shaft, for example, eccentric members thereof.

It is, however, particularly favorable when the slide coatings with lubrication deficiency properties are provided on the drive elements.

These drive elements are, for example, connecting rods, slide coatings of this type being provided in the connecting rod eye of these connecting rods which engages on the piston drive shaft.

In addition, it is preferably provided for the drive elements to be mounted on the pistons with slide bearings which have slide coatings with lubrication deficiency properties.

In this case, as well, a piston pin with a slide coating having such lubrication deficiency properties could be provided, for example, when connecting rods are used as drive elements.

A solution which is expedient with respect to the production does, however, provide for a connecting rod eye which engages on the piston pin and has a slide coating with lubrication deficiency properties to be provided.

The guidance of the pistons also requires customary lubrication.

In the solution according to the invention it is, however, likewise provided for the pistons to be guided on the cylinder working surfaces in a manner with lubrication deficiency properties.

Such a guidance of the pistons with lubrication deficiency properties could, for example, be realized in that the cylinder working surfaces are provided with a slide coating with lubrication deficiency properties.

A constructionally expedient solution provides for the pistons to have piston rings with lubrication deficiency properties which can then run directly on the cylinder working surfaces.

In addition or alternatively thereto, it is conceivable for the pistons to be provided with slide coatings with lubrication deficiency properties, in particular, on the piston skirt.

When such slide coatings with lubrication deficiency properties are provided for the guidance of the pistons, the refrigerant compressor according to the invention may, again, be designed advantageously in that with it the pistons are guided on the compressor housing without any cylinder liners, i.e., essentially directly in cylinder bores of the compressor housing.

The slide coatings with lubrication deficiency properties have not, themselves, been specified in greater detail in conjunction with the preceding explanations concerning the individual embodiments.

Slide coatings with lubrication deficiency properties are to be understood such that with them the lubrication with a lubricant can be interrupted for a defined period of time without damage occurring in the area of the respective slide bearings. In the extreme case, the slide coatings with lubrication deficiency properties are designed in such a manner that they are capable of running dry, i.e., are suitable for mounting without lubricant over a longer period of time.

One particularly advantageous embodiment of such slide coatings with lubrication deficiency properties provides for these to comprise PTFE, i.e., polytetrafluoroethylene.

In addition, these slide coatings with lubrication deficiency properties may be improved in that additives improving the stability of the PTFE, such as, for example, CaF, can be incorporated into it.

An additional, advantageous solution provides for the slide coatings with lubrication deficiency properties to comprise a porous layer consisting of sintered bronze which likewise has good lubrication deficiency properties.

A particularly favorable solution provides for PTFE to be incorporated into the porous layer consisting of sintered bronze.

With respect to the drive for the piston drive shaft, no further details have been given in conjunction with the preceding embodiments. It is, for example, particularly favorable for the design of the mounting for the piston drive shaft when this can be driven free from transverse forces on the drive side, i.e., forces directed transversely to the drive shaft axis since, as a result, the design of the mounting for the piston drive shaft need not take such transverse forces into consideration.

In this respect, it is particularly favorable when the piston drive shaft can be driven via a coupling, wherein the coupling is preferably designed as an electromagnetic coupling.

With respect to the drive for the coupling, it is provided for this to be drivable via a drive element.

In order to avoid the introduction of transverse forces into the piston drive shaft via such a coupling, it is preferably provided for the drive element of the coupling to be mounted, for its part, on the compressor housing via roller bearings. As a result, all the transverse forces acting on the drive element act on the compressor housing via the roller bearing but to a substantially reduced extent, if at all, on the piston drive shaft.

The drive element may be any type of drive element for a coupling. For example, this may be a drive wheel for the coupling as well as, for example, a drive pinion.

An alternative form of a drive element, in particular, for use in motor vehicles, provides for the drive element to be a belt pulley, with which transverse forces occur to a considerable degree on account of the belt tension.

Additional features and advantages of the invention are the subject matter of the following description as well as the drawings illustrating one embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through one embodiment of a refrigerant compressor according to the invention;

FIG. 2 shows a section along line 2-2 in FIG. 1;

FIG. 3 shows a section along line 3-3 in FIG. 1;

FIG. 4 shows a section through a slide coating used in bearing points of the refrigerant compressor according to the invention;

FIG. 5 shows a section along line 5-5 in FIG. 1;

FIG. 6 shows a perspective illustration of a housing cover illustrated in FIG. 5;

FIG. 7 shows a section along line 7-7 in FIG. 5;

FIG. 8 shows an enlarged, sectional illustration in the area around a piston drive shaft along line 8-8 in FIG. 3;

FIG. 9 shows a section along line 9-9 in FIG. 2 and

FIG. 10 shows a section along line 10-10 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of a refrigerant compressor for motor vehicles according to the invention, illustrated in FIG. 1, comprises a compressor housing which is designated as a whole as 10 and comprises a housing member 12 which is closed on one side with a first housing cover 14 and on a side located opposite by a second housing cover 16.

The compressor housing 10 can be divided altogether into a cylinder section 20 which comprises, for example, two cylinder banks 22 and 24 (FIG. 2) and a drive shaft section 26, which is located beneath the cylinder section 20 in a vertical direction in the installed position and in which a piston drive shaft designated as a whole as 30 is mounted for rotation about a drive shaft axis 32.

In this respect, the piston drive shaft 30 is mounted in the area of a first bearing point 34 which is arranged in the housing member 12 on a side facing the housing cover 14 and a second bearing point 36 which is arranged on the second housing cover 16.

The bearing point 34 is formed by a first annular member 40, which is preferably integrally formed in one piece on the housing member 12 and into which a first slide bearing bushing 42 with a slide coating 44 with lubrication deficiency properties is inserted, wherein the piston drive shaft 30 is slidingly mounted in the slide bearing bushing 42 with an outer surface designed as a first slide surface 45. The first slide surface 45 is provided in a first bearing section 46 of the piston drive shaft 30.

The second bearing point 36 is formed by a second annular member 50 which is integrally formed in one piece on the second housing cover 16. A second slide bearing bushing 52 with a slide coating with lubrication deficiency properties is seated in the second annular member 50, the piston drive shaft 30 being mounted in this second slide bearing bushing with an outer surface of a second bearing section 56 of the piston drive shaft 30, this outer surface being designed as a second slide surface 55.

The piston drive shaft 30 is, for its part, provided, for example, with a first eccentric member 60 and a second eccentric member 62, wherein a first connecting rod 64 and a second connecting rod 66 are mounted on the first eccentric member 60 while a third connecting rod 68 and a fourth connecting rod 70 are mounted on the second member so as to be rotatable.

As illustrated in FIG. 2, the third connecting rod 68 drives, for example, a piston 80 of the cylinder bank 24 while the fourth connecting rod 70 drives a piston 80 of the cylinder bank 22.

In the same way, the first connecting rod 64 drives a piston of the cylinder bank 24 and the second connecting rod 66 a piston of the cylinder bank 22.

Each of the connecting rods 64, 66, 68, 70 is mounted with its large connecting rod eye 82 on the respective eccentric member 60, 62 in the form of a slide bearing while a small connecting rod eye 84 of the respective connecting rod is mounted on the respective piston 80 via a piston pin 86 so as to be rotatable.

In this respect, the mounting of the small connecting rod eye 84 on the piston pin 86 is also designed as a slide bearing.

The large connecting rod eye 82 and the small connecting rod eye 84 are each preferably provided with a slide coating 88 with lubrication deficiency properties.

Each of the pistons 80 is, for its part, as illustrated in FIG. 2, guided for displacement in a cylinder working surface 100 of a cylinder bore 98, namely preferably at least via one piston ring 102 which is arranged in the piston skirt 104 close to a piston crown 106. Furthermore, the respective piston 80 is preferably guided, in addition, by an outer surface 108 of the piston skirt 104 which is arranged on a side of the piston ring 102 located opposite the piston crown 106.

The piston ring 102 is preferably designed such that its outer side 110 sliding on the cylinder working surface 100 is formed by a material comprising PTFE, wherein the cylinder working surface 100 is, for example, designed as a machined and, in particular, hardened aluminum outer surface of the housing member 12 produced from a cast aluminum.

In addition, the outer surface 108 of the piston skirt 104 is also provided, for example, with a slide coating 112 comprising PTFE.

As a result of the design of the piston ring 102 as described with an outer side 110 comprising PTFE and the slide coating 112 with a material comprising PTFE, the piston 80 is also guided altogether in the cylinder bore 98 in a manner with lubrication deficiency properties.

The cylinder bore 98 is, for its part, closed by a valve plate 116, on which the valves, which are not illustrated in the drawings, are seated and are, for their part, covered by a cylinder head cover 118.

The drive for the piston drive shaft 30 results via a drive section 120 of the piston drive shaft 30 which extends on a side of the first bearing point 34 located opposite the second bearing point 36 and beyond it and which, for its part, passes through a slide ring seal 122 which is arranged in a shoulder 126 of the first housing cover 14 forming a slide ring seal chamber 124.

A coupling disk 130 of an electromagnetic coupling designated as a whole as 132 is arranged on an end section 128 of the piston drive shaft 30 projecting out of the compressor housing 10 beyond the slide ring seal 122, wherein the coupling disk 130 is held on a coupling collar 138 seated on the end section 128 via a flexible ring 136.

Furthermore, the electromagnetic coupling 132 comprises a drivable belt disk 140 which is mounted, for its part, via roller bearings 142 on the shoulder 126 of the first housing cover 14 so as to be rotatable.

The belt disk 140 comprises, in addition, an annular section 144, on which the coupling disk 130 can be abutted in a friction-locking manner, namely by means of an electromagnet 146 which is arranged on a side of the annular section 144 of the belt disk 140 located opposite the coupling disk 130 and is held stationarily on the shoulder 126.

As a result of current being supplied to the electromagnet 146, the coupling disk 130 is drawn against the annular section 144 of the belt disk 140 and abutted on it in a friction-locking manner and, as a result, is taken along by the driven belt disk 140, wherein all the forces acting on the belt disk 140 on one side by means of the belt drive and directed transversely to the drive shaft axis 32 are absorbed by the roller bearing 142 for the belt disk 140.

The drive section 120 of the piston drive shaft 30 is driven by the coupling disk 130 via the flexible ring 136 and the coupling collar 138 free from external transverse forces caused, in particular, by the belt drive and so no such transverse forces need be absorbed, in particular, in the area of the first bearing point 34.

The only transverse forces to be absorbed by the piston drive shaft 30 and, therefore, the bearing points 34 and 36 result from the drive of the pistons 80 via the connecting rods 64, 66, 68, 70.

As illustrated in FIG. 4 on an enlarged scale, the slide coatings 44, 54 are built up such that they have a carrier member 150 consisting of steel, on which a porous layer 152 consisting of sintered bronze is arranged, wherein a material 156, comprising PTFE (polytetrafluoroethylene) and additional materials, is introduced, for example, rolled into pores or spaces 154 of the layer 152 consisting of sintered bronze so as to fill them and so the porous layer 152 consisting of sintered bronze is present on a slide surface 158 of such slide coatings 44, 54 together with the material 156 comprising PTFE and together they result in lubrication deficiency or at least temporarily dry running properties on the slide surface 158 so that the respective slide surfaces 45, 55 abutting thereon can also be guided and supported by the slide surface 158 or on the slide surface 158 without lubricant for an appreciable period of time essentially free from wear and tear.

Such a construction of a slide surface 158 with lubrication deficiency properties or dry running properties is preferably provided not only in conjunction with the slide bearing coatings 44 and 54 but also in the area of the large connecting rod eye 82 and the small connecting rod eye 84 of the respective connecting rods 64, 66, 68, 70 as a slide coating 88 as well as preferably in the case of the slide coating 112 on the piston skirt 104 and in the case of the construction of the piston ring 102, as well.

Despite the slide coatings 44, 54, 88, 112 with deficient lubricant properties and the piston rings 102 in the compressor according to the invention, this also operates with lubricant which is supplied to the individual slide bearings in the compressor housing 10 at least in part by means of a lubricant conveying device 160.

The lubricant conveying device 160 comprises a lubricant pitching disk 162 which is rotatable with the piston drive shaft 30 coaxially to the drive shaft axis 32. For this purpose, the lubricant pitching disk 162 is held on an imbalance compensation member 164 of the piston drive shaft 30 and is seated close to the second housing cover 16, wherein the lubricant pitching disk 162 engages around the annular member 50 of the second bearing point 36 integrally formed on the second housing cover 16 on its outer side (FIG. 1).

The lubricant pitching disk 162 thereby dips into a lubricant sump 166 which is formed in the interior of the compressor housing 10 and pitches the lubricant out of the lubricant sump 166 against an inner side 168 of the second housing cover 16, wherein the inner side 168 has ribs 170 (FIGS. 5, 6, 7) which extend radially to the drive shaft and between which collecting surfaces 172 are arranged which are located so as to be set back in relation to the ribs 170 and form together with the ribs 170 collecting pockets 174 which are recessed into the second housing cover 16, wherein the collecting pockets 174 are located merely between the ribs 170 which extend in a vertical direction above the piston drive shaft 30 in the installed position of the refrigerant compressor. The lubricant pitched into the collecting pockets 174 by the lubricant pitching disk 162 sticks at least partially to the collecting surfaces 172 and runs down the collecting surfaces 172 and, where applicable, guided by the ribs 170 in the direction of the piston drive shaft 30 as a result of gravity.

The collecting surfaces 172 extend as far as into a receiving chamber 176 for the lubricant which, as is apparent from FIGS. 1 and 7, is arranged in the second housing cover 16 facing an end side 178 of the piston drive shaft and being open towards it.

Proceeding from the end side 178 of the piston drive shaft 30, a central lubricant channel 180 extending coaxially to the drive shaft axis 32 extends into it, namely preferably from the end side 178 as far as into the drive section 120, wherein lubricant supply channels extending radially to the drive shaft axis 32 branch off the lubricant channel 180.

These are, for example, lubricant supply channels 182 and 184 which are provided in the first bearing section 46 and the second bearing section 56 and which have openings 186, 188 located in the slide surfaces 45 and 55, respectively, via which lubrication of the sliding mounting of the slide surfaces 45 and 55, respectively, on the slide coatings 44, 54 of the slide bearing bushings 42 and 52, respectively, is brought about.

In addition, lubricant supply channels 190, 192, 194 and 196 preferably branch off the central lubricant channel 180, as well, and these supply channels contribute to the lubrication of the large connecting rod eyes 82 of the individual connecting rods 64, 66, 68, 70, which are slidingly mounted on slide surfaces 200, 202, 204, 206 with their slide coatings 88, with respective openings 210, 212, 214, 216 which are located in the slide surfaces 200, 202, 204, 206 for the connecting rods 64, 66, 68, 70 (FIG. 1).

Lubrication in the area of the slide coatings 88 of the small connecting rod eyes 84 and the slide coatings 112 as well as the piston rings 102 of the pistons 80 is brought about by a lubricant mist generated by the lubricant pitching disk 162 in the compressor housing 10.

Finally, a lubricant supply channel 220, which serves to supply the slide ring seal 122 with lubricant, also branches off the central lubricant channel 180.

As illustrated, in addition, in FIG. 1, the slide ring seal chamber 124 in the shoulder 126 is designed such that the lubricant exiting from the slide ring seal 122 is collected and accumulates in it, wherein the entire slide ring seal 122 is preferably arranged so as to dip into the lubricant accumulating in the slide ring seal chamber 124 and it is possible for the lubricant to leave the slide ring seal chamber 124 only via an overflow channel 222 arranged above the first annular member 40.

The lubricant passing through the slide ring seal 122 is, as illustrated in FIG. 8, collected in a space 125 between the slide ring seal 122 and an outer shaft seal 123 and supplied to a cavity 219 via a channel 218.

All the lubricant which accumulates within a cylinder chamber 224 enclosed by the cylinder section 20 of the compressor housing 10 and within a drive shaft chamber 226 enclosed by the drive shaft section 26, wherein the cylinder chamber 224 and the drive shaft chamber 226 merge into one another, is collected as a result of gravity in a pan 228 which is formed by the drive shaft section 26 and which, as illustrated in FIG. 1, extends in the direction of the drive shaft axis 32 from the side of the first bearing point 34 in the direction towards the second housing cover 16 and forms a collection chamber 230, in which the lubricant collects to form the lubricant sump 166, directly adjoining the second housing cover 16. In this respect, the pan 228 is preferably inclined with its wall surfaces 232 and the base surface 234 in the direction of the collection chamber 230 in order to guide all the lubricant entering the pan 228 to the collection chamber 230 as a result of gravity.

The lubricant flowing out of the slide ring seal chamber 124 out of the overflow channel 222 also runs around the first annular member 40 into the pan 228 and is supplied to the collection chamber 230. In addition, the lubricant collecting in the cavity 219 is also supplied to the drive shaft chamber 226 via a channel 236.

The collection chamber 230 is preferably designed such that the lubricant collecting in it to form the lubricant sump 166 can still be taken up by the lubricant pitching disk 162 and pitched into the collecting pockets 174 even with an inclination of the drive shaft axis in relation to the ideal installation position through up to plus/minus 35°, preferably up to plus/minus 15° in a vertical direction or also rotation of the compressor housing about the drive shaft axis 22 through up to plus/minus 90°, preferably up to plus/minus 45° in relation to the optimum installation position.

Since lubricant is transported along with the refrigerant according to the invention, this entrained lubricant will also be supplied again, at least in part, via refrigerant drawn in.

Lubricant is also supplied, for example, by way of refrigerant entering the compressor housing via a suction gas channel 240 and this lubricant will already be precipitated in the central suction gas channel 250 and then enters the branch channels 242, 244 leading to the cylinder banks 22, 24.

These branch channels 242, 244 have, for their part, as illustrated, in particular, in FIGS. 2 and 7, collecting areas 246, 248, proceeding form which lubricant can enter the cylinder chamber 224 via discharge channels 250, 252 and from there can be guided to the pan 228 so that the lubricant again supplied to the refrigerant compressor by the refrigerant can also be collected in the collection chamber 230.

Finally, the refrigerant compressed in the refrigerant compressor flows via branch channels 256, 258 into a central pressure gas channel 260, proceeding from which it exits from the compressor housing 10 via a pressure gas connection 162 (FIGS. 3, 9).

In order to insulate the central pressure gas channel 260 heated up by hot pressure gas in relation to the cylinder bores 98 and the suction gas channel 240, hollow housing pockets 270 are integrally formed in the housing member 12 and these are connected to the cylinder chamber 224 only by a pressure compensation channel 272 so that the gaseous medium, which is essentially not swirled about in this channel but is, in particular, static, brings about a thermal insulation (FIGS. 9, 10). 

1. Refrigerant compressor for motor vehicles comprising a compressor housing, at least two cylinder bores arranged in the compressor housing, pistons arranged in the cylinder bores, a drive shaft chamber arranged in the compressor housing as well as a piston drive shaft arranged in the drive shaft chamber, wherein in the installed position of the refrigerant compressor the drive shaft chamber forms a collection chamber for lubricant with an area extending over only part of the extension of the drive shaft chamber and being located at the lowest point in the direction of gravity, wherein the drive shaft chamber has wall surfaces adjoining the collection chamber, said wall surfaces guiding the lubricant accumulating in the drive shaft chamber to the collection chamber, and wherein a lubricant conveying device takes up the lubricant from the collection chamber and conveys it to lubrication points.
 2. Refrigerant compressor as defined in claim 1, wherein the wall surfaces guide essentially all the lubricant accumulating in the drive shaft chamber to the collection chamber.
 3. Refrigerant compressor as defined in claim 1, wherein some of the wall surfaces extend at an angle to a drive shaft axis of the piston drive shaft.
 4. Refrigerant compressor as defined in claim 1, wherein the collection chamber borders on a housing cover of the compressor housing.
 5. Refrigerant compressor as defined in claim 4, wherein the housing cover extends transversely to the drive shaft axis of the piston drive shaft.
 6. Refrigerant compressor as defined in claim 1, wherein the drive shaft chamber is located beneath a cylinder chamber of the compressor housing in the direction of gravity in the installed position of the compressor.
 7. Refrigerant compressor as defined in claim 6, wherein the cylinder chamber is designed in such a manner that lubricant accumulating in it essentially enters the drive shaft chamber.
 8. Refrigerant compressor as defined in claim 1, wherein the collection chamber is integrally formed in a drive shaft section of the compressor housing.
 9. Refrigerant compressor as defined in claim 1, wherein the wall surfaces guiding the lubricant to the collection chamber are integrally formed in the drive shaft section.
 10. Refrigerant compressor as defined in claim 8, wherein the drive shaft section of the compressor housing forms a pan inclined towards the collection chamber.
 11. Refrigerant compressor as defined in claim 1, wherein the collection chamber always remains the subsection of the drive shaft section located at the lowest point with an inclination of a drive shaft axis of up to at the most plus/minus 35° in relation to the installed position.
 12. Refrigerant compressor as defined in claim 1, wherein the collection chamber always collects the lubricant with an inclination of the compressor housing about the drive shaft axis of the piston drive shaft of up to at the most plus/minus 90° in relation to the installed position.
 13. Refrigerant compressor as defined in claim 1, wherein the lubricant conveying device comprises a lubricant pitching disk engaging in the collection chamber.
 14. Refrigerant compressor as defined in claim 13, wherein the lubricant pitching disk is driven by the piston drive shaft.
 15. Refrigerant compressor as defined in claim 14, wherein the piston drive shaft bears the lubricant pitching disk.
 16. Refrigerant compressor as defined in claim 13, wherein the lubricant pitching disk is arranged close to the compressor housing cover located nearest to the collection chamber.
 17. Refrigerant compressor as defined in claim 13, wherein the lubricant pitching disk extends essentially vertically in the installed position.
 18. Refrigerant compressor as defined in claim 13, wherein the lubricant conveying device has a receiving chamber for lubricant pitched by the lubricant pitching disk.
 19. Refrigerant compressor as defined in claim 18, wherein the receiving chamber is arranged such that lubricant pitched against a collecting surface and running down it enters said chamber.
 20. Refrigerant compressor as defined in claim 18, wherein the receiving chamber is arranged in the housing cover.
 21. Refrigerant compressor as defined in claim 18, wherein the collecting surface is arranged on the housing cover.
 22. Refrigerant compressor as defined in claim 19, wherein the lubricant conveying device has guide ribs guiding the lubricant into the receiving chamber.
 23. Refrigerant compressor as defined in claim 1, wherein the lubricant conveying device comprises a central lubricant channel integrated into the piston drive shaft.
 24. Refrigerant compressor as defined in claim 23, wherein lubricant is suppliable to the central lubricant channel from the receiving chamber.
 25. Refrigerant compressor as defined in claim 23, wherein the central lubricant channel is provided with lubricant supply channels for lubrication points of the piston drive shaft, said supply channels extending transversely to said lubricant channel.
 26. Refrigerant compressor as defined in claim 1, wherein the filling amount of the lubricant in the refrigerant compressor is less than double the capacity of the refrigerant compressor.
 27. Refrigerant compressor as defined in claim 26, wherein the filling amount of the lubricant is less than 1.5 times the capacity of the refrigerant compressor.
 28. Refrigerant compressor for motor vehicles comprising a compressor housing, at least two cylinder bores arranged in the compressor housing, pistons arranged in the cylinder bores, a drive shaft chamber arranged in the compressor housing as well as a piston drive shaft arranged in the drive shaft chamber, wherein the piston drive shaft is mounted in the compressor housing only in slide bearings and wherein the slide bearings have slide coatings with lubrication deficiency properties.
 29. Refrigerant compressor as defined in claim 28, wherein drive elements for the pistons are mounted on the piston drive shaft with slide bearings having slide coatings with lubrication deficiency properties.
 30. Refrigerant compressor as defined in claim 28, wherein the drive elements are mounted on the pistons with slide bearings having slide coatings with lubrication deficiency properties.
 31. Refrigerant compressor as defined in claim 28, wherein the pistons are guided on the cylinder working surfaces in a manner with lubrication deficiency properties.
 32. Refrigerant compressor as defined in claim 31, wherein the pistons have piston rings with lubrication deficiency properties.
 33. Refrigerant compressor as defined in claim 31, wherein the pistons are provided with slide coatings with lubrication deficiency properties.
 34. Refrigerant compressor as defined in claim 31, wherein the pistons are guided on the compressor housing without any cylinder liners.
 35. Refrigerant compressor as defined in claim 28, wherein the slide coatings with lubrication deficiency properties comprise PTFE.
 36. Refrigerant compressor as defined in claim 35, wherein additives improving the stability of the PTFE are incorporated into it.
 37. Refrigerant compressor as defined in claim 28, wherein the slide coatings with lubrication deficiency properties comprise a porous layer consisting of sintered bronze.
 38. Refrigerant compressor as defined in claim 37, wherein PTFE is incorporated into the porous layer consisting of sintered bronze.
 39. Refrigerant compressor as defined in claim 1, wherein the piston drive shaft is drivable free from transverse forces on the drive side.
 40. Refrigerant compressor as defined in claim 39, wherein the piston drive shaft is drivable via a coupling.
 41. Refrigerant compressor as defined in claim 40, wherein the coupling is drivable via a drive element.
 42. Refrigerant compressor as defined in claim 41, wherein the drive element is for its part mounted on the compressor housing via roller bearings. 